In a package dyeing operation, yarn is wound onto special tubes or cores and the resulting yarn package is dyed as a unit. The tubes or cores are generally tubular and include a plurality of holes through the bodywall to allow dye to flow from the interior of the dye tube radially outward through the yarn wound about the tube.
The package dyeing operation involves mounting a number of yarn packages upon a generally tubular spindle of the package dyeing apparatus. The packages are mounted on the spindle so that the spindle extends substantially coaxially through the dye tube of each yarn package. The spindle also has a number of holes to allow dye to pass from its interior outwardly to the yarn packages. A first end of the spindle is rotatably affixed to a base while the second end of the spindle is covered by a cap. The yarn packages placed on the spindle are axially compressed between the cap and the base.
In operation, dye is forced under pressure from a dye source or reservoir through the spindle. The dye is subsequently forced through the holes of both the spindle and the dye tubes, thus, permeating and dyeing the yarn wound upon the dye tubes. In order to maintain consistent dyeing of the yarn, a substantially equal amount of dye under substantially equal pressure must be presented to each yarn package.
The maintenance of substantially equal dye pressures for each package is accomplished, in part, by the use of spacer rings. The spacer rings are coaxially mounted on the spindle between adjacent yarn packages and function both to space the yarn packages apart and to seal the end faces of the yarn packages. In order to prevent dye leaks between adjacent packages and a resulting loss of dye pressure, the spacer rings must reliably seal each end face of the dye tubes.
In the past, dye tubes as well as spacer rings were typically formed of metallic materials. The walls of the metallic dye tubes are generally relatively thin, such as 1.2 mm to 1.8 mm, due to the strength of the metal. Metallic spacer rings typically have a center cylindrical portion and frustoconical shaped peripheral edges that taper from a relatively large axial thickness adjacent the center cylindrical portion to a relatively small axial thickness at the periphery. The diameter of the cylindrical portion of the ring is less than the inside diameter of the dye tube although the overall diameter of the spacer ring is larger than the inside diameter of the dye tube.
In use, the central cylindrical faces of the spacer rings are inserted into the open ends of adjacent dye tubes. The end face of each dye tube is thereby seated on the tapered sidewall of a spacer ring. The spacer ring thus axially aligns and seals adjacent dye tubes by tangentially contacting the interior surface of the end face of the dye tube substantially continuously about the circumference of the end face.
Due to the relatively high strength of the metallic spacer rings and dye tubes, the yarn packages can be placed under substantial axial pressure in order to improve the seal between the spacer rings and the dye tubes without structurally damaging them. This increased axial pressure also causes slight inward bowing of the tapered sidewall of the spacer ring. The bowing of the sidewalls further improves the seal since tangential contact is established over a broader surface area of the end face of the dye tube and the tapered sidewall of the spacer ring.
More recently, dye tubes have been formed of plastic materials. Although yarn packages having plastic dye tubes must also be properly sealed in order to dye the yarn consistently, plastic dye tubes cannot withstand as much axial pressure as metallic dye tubes without being structurally damaged. Accordingly plastic dye tubes which are mounted upon a spindle are more likely than metal tubes to suffer damage. However decreasing the axial compression applied to the tubes in order protect them can inhibit effective sealing between the plastic dye tubes and the spacer rings.